1. Field of the Invention
This invention relates to optical interconnection apparatus (optical circuit board) for mutually connecting optical components, parts and/or devices used in optical communications or optical information processing, such as optical components, optical circuit packages and optical circuit devices.
2. Description of the Background Art
To permit optical interconnections between plural optical components in an optical circuit package or optical interconnections between plural optical circuit packages or between optical circuit devices on each of which optical packages are mounted, these optical components, optical circuit packages and optical circuit devices are provided at terminals thereof with optical connectors to interconnect them together via optical fibers. As these optical fibers have to be arranged with a surplus in length in this case, it is a current circumstance that, on an optical circuit package or inside and/or on a back side of an optical circuit devices, intricately routed lines of the optical fibers extend overlapping one another in the form like bird's nest and hence occupy a large space. For an optical interconnection process which requires a large space and considerable interconnecting labor due to such complex routing, a simple process has been proposed to solve these problems by routing optical fibers on a two-dimensional planar surface as desired. As disclosed in JP 2,574,611 B, for example, an optical interconnection apparatus which uses a sheet or base with a pressure-sensitive adhesive coated thereon to hold optical fibers in place has been proposed.
The optical interconnection apparatus disclosed in JP 2,574,611 B is obtained in such a way that upon its fabrication, optical fibers are routed by a pressure-sensitive adhesive, which is coated on a substrate (base layer) or a fiber jacket to form a routing pattern and the routing pattern is then covered with the same material with the same size as the material used for the substrate, whereby a protective layer (covering layer) is formed. This process is however accompanied by problems in that optical fibers outwardly extended from the substrate become easy to bend extremely at the edges of the substrate to cause breakage of the optical fibers or increase transmission loss, because the routed optical fibers outwardly extended at the edges of the substrate are sandwiched with two substrates so that flexibility of the optical interconnection apparatus is uniform over the whole area and stiffness thereof becomes much larger than that of optical fibers. Therefore, there are big problems in handling and reliability.